Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 106 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) dipping the cotton bud (c) putting the iron away (d) ironing the paper
2. 2.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
3. 3.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) the ink is magnetic (d) it turned into air
4. 4.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) reading the message (d) ironing the paper
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
6. 6.🔍 Which is the odd one out? (a) putting the iron away (b) writing the message (c) plugging in the iron (d) ironing the paper
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) a cotton bud (d) a magnet
8. 8.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) any child (c) the youngest child (d) whoever is fastest
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a balloon (d) a cotton bud
11. 11.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
12. 12.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
15. 15.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) writing stays faint (d) the paper floats
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
17. 17.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
18. 18.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) an adult with an iron (d) a magnet
19. 19.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) a small bowl (c) an adult with an iron (d) lemon juice
22. 22.🍋 Which of these steps is a job for an adult? (a) writing the message (b) ironing the paper (c) dipping the cotton bud (d) reading the message
23. 23.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
24. 24.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it is cold (d) it can burn skin
25. 25.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) ironing the paper (d) letting the paper dry
26. 26.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
28. 28.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
29. 29.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) reading the message (c) plugging in the iron (d) ironing the paper
30. 30.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) plugging in the iron (d) dipping the cotton bud
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we change it (c) we keep it the same
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) how dark the writing is (c) the kind of juice
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) an adult with an iron (c) lemon juice (d) turmeric powder
36. 36.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) lick your fingers (d) wash your hands
37. 37.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) reading the message (d) ironing the paper
38. 38.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) yeast (d) a mirror
39. 39.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) musical (d) chemical
40. 40.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) yeast (c) a magnet (d) a battery cell

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