Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 841 · 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.🍋 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
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
3. 3.🛟 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
4. 4.⚖️ 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 measure it (c) we keep it the same
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 cotton bud (c) turmeric powder (d) lemon juice
6. 6.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) yeast (c) a mirror (d) lemon juice
7. 7.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
8. 8.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) whoever is fastest (c) the youngest child (d) any child
9. 9.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
10. 10.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) a battery cell (c) a magnet (d) turmeric powder
13. 13.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) chemical (d) magnetic
14. 14.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
15. 15.True or false: letting the paper dry is a job a child can do. (a) True (b) False
16. 16.🍋 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) ironing the paper
17. 17.True or false: white paper is needed for the secret lemon message. (a) False (b) True
18. 18.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
19. 19.🔍 Which is the odd one out? (a) cutting the lemon (b) letting the paper dry (c) ironing the paper (d) plugging in the iron
20. 20.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
21. 21.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, if cooled (d) yes, in the dark
22. 22.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) letting the paper dry (d) putting the iron away
23. 23.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
24. 24.⚖️ 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 ironing time (c) the kind of juice
25. 25.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
26. 26.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
27. 27.True or false: plugging in the iron is a job for an adult. (a) False (b) True
28. 28.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
29. 29.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
31. 31.True or false: yeast is needed for the secret lemon message. (a) False (b) True
32. 32.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) a balloon (d) an adult with an iron
33. 33.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
34. 34.True or false: reading the message is a job for an adult. (a) False (b) True
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
36. 36.⚖️ 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 ironing time (c) how dark the writing is (d) the iron setting
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
38. 38.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) dipping the cotton bud (d) letting the paper dry
39. 39.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the same paper (c) the kind of juice (d) the same cotton bud

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