Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 342 · 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 mirror for the secret lemon message? (a) needed (b) not needed
2. 2.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) plugging in the iron (d) dipping the cotton bud
3. 3.True or false: putting the iron away is a job a child can do. (a) False (b) True
4. 4.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) letting the paper dry (d) putting the iron away
5. 5.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
6. 6.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) it gets darker (d) writing stays faint
7. 7.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) physical (c) chemical (d) magnetic
8. 8.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) only an adult (d) whoever is fastest
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we keep it the same (c) we measure it
10. 10.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) dipping the cotton bud (d) ironing the paper
11. 11.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) ironing the paper (c) reading the message (d) dipping the cotton bud
12. 12.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
13. 13.⚖️ 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
14. 14.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
15. 15.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) a cotton bud (d) a battery cell
16. 16.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) putting the iron away (d) writing the message
17. 17.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a small bowl (c) turmeric powder (d) a mirror
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.⚖️ 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 same cotton bud (c) the ironing time (d) the iron setting
20. 20.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
21. 21.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) reading the message (d) putting the iron away
22. 22.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) yes, in the dark (d) no, it stays brown
23. 23.🔍 Which is the odd one out? (a) cutting the lemon (b) letting the paper dry (c) ironing the paper (d) plugging in the iron
24. 24.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
25. 25.True or false: reading the message is a job a child can do. (a) False (b) True
26. 26.True or false: letting the paper dry is a job for an adult. (a) False (b) True
27. 27.True or false: cutting the lemon is a job a child can do. (a) True (b) False
28. 28.🍋 Which of these steps is a job a child can do? (a) writing the message (b) ironing the paper (c) plugging in the iron (d) putting the iron away
29. 29.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
30. 30.⚖️ 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
31. 31.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
32. 32.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) almost nothing (c) dark brown words (d) a rainbow
33. 33.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
34. 34.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a mirror (c) a cotton bud (d) a small bowl
36. 36.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) turmeric powder (c) a balloon (d) white paper
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is
38. 38.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
39. 39.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
40. 40.⚖️ 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

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