Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 689 · 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.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a cotton bud (c) a battery cell (d) a magnet
2. 2.True or false: white paper is needed for the secret lemon message. (a) False (b) True
3. 3.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
4. 4.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
5. 5.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
6. 6.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) dipping the cotton bud (d) putting the iron away
7. 7.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if cooled (d) yes, if shaken
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a magnet (c) a small bowl (d) white paper
9. 9.⚖️ 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 ironing time (c) the iron setting (d) the same cotton bud
10. 10.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
11. 11.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) wash your hands (d) skip washing
12. 12.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the iron is brown (c) the juice scorches first (d) heat adds colour
13. 13.🔍 Which is the odd one out? (a) plugging in the iron (b) letting the paper dry (c) putting the iron away (d) ironing the paper
14. 14.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
15. 15.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) plugging in the iron (d) reading the message
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a mirror (c) a cotton bud (d) lemon juice
18. 18.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) whoever is fastest (d) any child
19. 19.🍋 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
20. 20.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
21. 21.True or false: putting the iron away is a job a child can do. (a) False (b) True
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) how dark the writing is (c) the same paper (d) the same cotton bud
23. 23.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
24. 24.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) a small bowl (d) a mirror
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a balloon (c) a small bowl (d) lemon juice
26. 26.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) a cotton bud (c) lemon juice (d) an adult with an iron
28. 28.🍋 Which of these steps is a job for an adult? (a) reading the message (b) ironing the paper (c) letting the paper dry (d) writing the message
29. 29.True or false: plugging in the iron is a job for an adult. (a) True (b) False
30. 30.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
31. 31.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is cold (d) it is magnetic
32. 32.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) turmeric powder (d) a cotton bud
33. 33.True or false: writing the message is a job a child can do. (a) True (b) False
34. 34.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) physical (c) musical (d) magnetic
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we change it (c) we measure it
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
37. 37.⚖️ 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
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we measure it (c) we change it
39. 39.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
40. 40.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) white paper (c) a battery cell (d) a balloon

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