Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 634 · 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.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) skip washing (d) wash your hands
2. 2.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) dry juice is see-through (d) the ink is magnetic
3. 3.⚖️ 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
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
5. 5.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) lemon juice (c) yeast (d) turmeric powder
6. 6.⚖️ 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 iron setting (c) how dark the writing is (d) the kind of juice
7. 7.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) letting the paper dry
8. 8.True or false: putting the iron away is a job a child can do. (a) True (b) False
9. 9.🧺 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 balloon
10. 10.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) the paper floats (d) writing stays faint
11. 11.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) a small bowl (c) lemon juice (d) an adult with an iron
13. 13.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
14. 14.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) dipping the cotton bud
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
16. 16.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) dipping the cotton bud (c) writing the message (d) letting the paper dry
17. 17.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) yeast (c) turmeric powder (d) a balloon
18. 18.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
20. 20.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) dipping the cotton bud (d) cutting the lemon
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) turmeric powder (c) lemon juice (d) white paper
22. 22.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
23. 23.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) dark brown words (d) blue words
24. 24.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
25. 25.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
27. 27.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) physical (d) chemical
28. 28.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
29. 29.True or false: cutting the lemon is a job a child can do. (a) False (b) True
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the kind of juice (c) the ironing time (d) how dark the writing is
31. 31.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
32. 32.True or false: plugging in the iron is a job a child can do. (a) True (b) False
33. 33.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
34. 34.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) dipping the cotton bud (c) plugging in the iron (d) ironing the paper
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) yeast (d) white paper
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a battery cell (d) an adult with an iron
37. 37.True or false: cutting the lemon is a job for an adult. (a) False (b) True
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
39. 39.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
40. 40.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is sticky (c) it is cold (d) it is magnetic

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