Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 421 · 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 for an adult. (a) True (b) False
2. 2.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the ink is magnetic (c) it turned into air (d) the paper ate it
3. 3.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
4. 4.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) writing the message (c) letting the paper dry (d) dipping the cotton bud
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a magnet (c) white paper (d) lemon juice
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) white paper (c) a battery cell (d) lemon juice
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the iron setting (c) the kind of juice (d) the same paper
8. 8.⚖️ 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
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) turmeric powder (c) a cotton bud (d) a small bowl
10. 10.⚖️ 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
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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the same paper
13. 13.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) reading the message (c) plugging in the iron (d) cutting the lemon
14. 14.True or false: putting the iron away is a job a child can do. (a) True (b) False
15. 15.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
17. 17.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
18. 18.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
19. 19.🍋 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) plugging in the iron
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the iron setting (c) the kind of juice
21. 21.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
22. 22.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
23. 23.🔍 Which is the odd one out? (a) dipping the cotton bud (b) cutting the lemon (c) letting the paper dry (d) writing the message
24. 24.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
25. 25.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) writing the message (d) cutting the lemon
26. 26.⚖️ 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
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we change it (c) we measure it
28. 28.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
29. 29.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) musical (c) physical (d) magnetic
30. 30.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) letting the paper dry (d) plugging in the iron
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) lemon juice (d) a battery cell
32. 32.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) the juice scorches first (d) paper turns lemony
33. 33.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
34. 34.⚖️ 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 keep it the same (c) we change it
35. 35.⚖️ 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
36. 36.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) skip washing (d) wash your hands
37. 37.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
38. 38.True or false: ironing the paper is a job a child can do. (a) True (b) False
39. 39.True or false: plugging in the iron is a job for an adult. (a) True (b) False
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a mirror (c) white paper (d) lemon juice

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