Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 911 · 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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the same cotton bud (c) the ironing time (d) the kind of juice
2. 2.🔍 Which is the odd one out? (a) writing the message (b) letting the paper dry (c) ironing the paper (d) reading the message
3. 3.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
4. 4.True or false: ironing the paper is a job a child can do. (a) True (b) False
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
6. 6.True or false: reading the message is a job a child can do. (a) False (b) True
7. 7.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if cooled (c) yes, if shaken (d) no, it stays brown
8. 8.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) dipping the cotton bud (d) plugging in the iron
9. 9.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) it turned into air (c) the paper ate it (d) the ink is magnetic
10. 10.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) only an adult (d) any child
11. 11.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) a battery cell (c) a balloon (d) a magnet
12. 12.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) cutting the lemon
13. 13.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) writing the message (d) plugging in the iron
14. 14.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
15. 15.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a mirror (c) an adult with an iron (d) white paper
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) True (b) False
18. 18.🛟 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
19. 19.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
20. 20.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) lemon juice (c) a balloon (d) a magnet
21. 21.True or false: putting the iron away is a job a child can do. (a) True (b) False
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we change it (c) we keep it the same
24. 24.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) lemon juice (c) a small bowl (d) white paper
25. 25.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a balloon (c) lemon juice (d) an adult with an iron
27. 27.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
28. 28.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) putting the iron away (d) dipping the cotton bud
29. 29.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
30. 30.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
31. 31.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
32. 32.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) False (b) True
34. 34.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) musical (d) chemical
35. 35.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
36. 36.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) reading the message
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) True (b) False
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
39. 39.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
40. 40.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) ironing the paper

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