Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 396 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a cotton bud (d) a balloon
2. 2.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
3. 3.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) an adult with an iron (c) white paper (d) a small bowl
5. 5.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
6. 6.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) letting the paper dry (d) dipping the cotton bud
7. 7.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the iron setting (c) how dark the writing is (d) the same paper
10. 10.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
11. 11.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) cutting the lemon (d) dipping the cotton bud
12. 12.True or false: writing the message is a job for an adult. (a) True (b) False
13. 13.🧺 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) a small bowl (d) lemon juice
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) a balloon (d) a small bowl
15. 15.⚖️ 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) False (b) True
16. 16.True or false: plugging in the iron is a job for an adult. (a) False (b) True
17. 17.⚖️ 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 iron setting
18. 18.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
19. 19.⚖️ 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) the same paper (d) how dark the writing is
20. 20.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) letting the paper dry (d) plugging in the iron
21. 21.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) letting the paper dry (c) writing the message (d) reading the message
22. 22.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) rub your eyes (d) lick your fingers
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) an adult with an iron (d) a mirror
24. 24.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) yeast (c) lemon juice (d) white paper
26. 26.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
27. 27.True or false: letting the paper dry is a job for an adult. (a) True (b) False
28. 28.True or false: white paper is needed for the secret lemon message. (a) False (b) True
29. 29.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
30. 30.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) yeast (d) a cotton bud
31. 31.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
32. 32.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) yes, if cooled (d) no, it stays brown
33. 33.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
34. 34.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) reading the message (d) putting the iron away
35. 35.🧺 Which of these is not needed for the secret lemon message? (a) yeast (b) a cotton bud (c) lemon juice (d) white paper
36. 36.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is
38. 38.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) putting the iron away (d) writing the message
39. 39.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) an adult with an iron (c) turmeric powder (d) a magnet
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True

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