Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 45 · 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.True or false: ironing the paper is a job a child can do. (a) True (b) False
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
3. 3.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) lick your fingers (c) rub your eyes (d) skip washing
4. 4.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) only an adult (d) whoever is fastest
5. 5.True or false: reading the message is a job a child can do. (a) False (b) True
6. 6.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) a cotton bud (d) a magnet
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) a cotton bud (c) white paper (d) an adult with an iron
8. 8.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) ironing the paper
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) turmeric powder (d) an adult with an iron
10. 10.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is sticky (d) it is magnetic
11. 11.⚖️ 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
12. 12.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) cutting the lemon (d) reading the message
13. 13.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
14. 14.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing stays faint (d) writing turns green
15. 15.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) no, it stays brown (d) yes, if cooled
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) lemon juice (d) a balloon
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a battery cell (d) a small bowl
18. 18.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) dipping the cotton bud (c) reading the message (d) letting the paper dry
19. 19.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) turmeric powder (c) a battery cell (d) an adult with an iron
20. 20.🍋 Which of these steps is a job a child can do? (a) reading the message (b) putting the iron away (c) ironing the paper (d) plugging in the iron
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) the kind of juice (c) how dark the writing is (d) the iron setting
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we change it (c) we measure it
23. 23.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
24. 24.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the kind of juice (c) the same cotton bud (d) the same paper
26. 26.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
27. 27.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) putting the iron away (d) letting the paper dry
28. 28.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a mirror (c) a magnet (d) a battery cell
29. 29.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) musical (d) chemical
30. 30.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) dry juice is see-through (c) it turned into air (d) the ink is magnetic
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we keep it the same (c) we measure it
32. 32.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
33. 33.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
34. 34.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
35. 35.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a battery cell (c) turmeric powder (d) a cotton bud
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a balloon (d) an adult with an iron
37. 37.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
38. 38.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
39. 39.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
40. 40.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a battery cell (c) yeast (d) a mirror

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