Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 347 · 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.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) lemon juice (c) white paper (d) a small bowl
3. 3.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) wash your hands (d) lick your fingers
4. 4.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a small bowl (c) turmeric powder (d) a battery cell
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) lemon juice (c) white paper (d) a small bowl
6. 6.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) cutting the lemon (d) ironing the paper
7. 7.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
8. 8.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
9. 9.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) reading the message (c) letting the paper dry (d) dipping the cotton bud
10. 10.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) writing the message (d) ironing the paper
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) yeast (c) lemon juice (d) an adult with an iron
12. 12.⚖️ 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
13. 13.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) putting the iron away (d) reading the message
14. 14.True or false: ironing the paper is a job for an adult. (a) True (b) False
15. 15.⚖️ 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 change it (c) we keep it the same
16. 16.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
17. 17.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
18. 18.⚖️ 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
19. 19.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
20. 20.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
22. 22.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) no, it stays brown (d) yes, in the dark
23. 23.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) reading the message (d) cutting the lemon
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
25. 25.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) the juice scorches first (c) paper turns lemony (d) heat adds colour
26. 26.True or false: cutting the lemon is a job for an adult. (a) True (b) False
27. 27.🛟 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
28. 28.True or false: putting the iron away is a job for an adult. (a) True (b) False
29. 29.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
30. 30.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing stays faint (c) the paper floats (d) writing turns green
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a magnet (c) a cotton bud (d) lemon juice
32. 32.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) lemon juice (c) white paper (d) a mirror
33. 33.⚖️ 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 keep it the same (c) we measure it
34. 34.⚖️ 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
35. 35.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
36. 36.⚖️ 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
37. 37.🍋 Which of these steps is a job for an adult? (a) writing the message (b) plugging in the iron (c) reading the message (d) dipping the cotton bud
38. 38.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
39. 39.⚖️ 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
40. 40.🔍 Which is the odd one out? (a) putting the iron away (b) dipping the cotton bud (c) ironing the paper (d) cutting the lemon

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